Need distance from bell housing face to face of pilot bearing

[KJL]

Trying to determine the engagement depth of the ZF transmission input shaft into the crank pilot bearing. What I need is the distance from the bell housing face to the face of the pilot bearing. Bearing needs to be at correct depth into crank (approx. 15mm).

Thanks!

[ssrszz4]

What are you up too

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[KJL]

When replacing my clutch, the bronze bushing dropped out into my hand. It appears to have been installed incorrectly but we don't know for sure. There is an odd wear mark around the inside perimeter of the bearing only about 0.25" in from the face of the bearing. Unfortunately I didn't notice it until after I installed the transmission. Sooooo, now I am curious to know how much engagement there is. This mark implies there is only 0.25" of engagement.

[WVZR-1]

Originally Posted by KJL

When replacing my clutch, the bronze bushing dropped out into my hand. It appears to have been installed incorrectly but we don't know for sure. There is an odd wear mark around the inside perimeter of the bearing only about 0.25" in from the face of the bearing. Unfortunately I didn't notice it until after I installed the transmission. Sooooo, now I am curious to know how much engagement there is. This mark implies there is only 0.25" of engagement.

I would think that you would/could use your input-shaft dimensions to actually confirm what your particular install is/was or what you feel you need to accomplish. You asked about this back in April I believe and got 14mm, 14.5mm. I'd think you would put the pilot you intend to use on your input-shaft and measure what is going to "individualize" your install. That would seem very easy to confirm using your after install measurement from the mating face of the clutch housing to that of "your" bearing in the crankshaft.

[Dynomite]

Originally Posted by WVZR-1

I would think that you would/could use your input-shaft dimensions to actually confirm what your particular install is/was or what you feel you need to accomplish. You asked about this back in April I believe and got 14mm, 14.5mm. I'd think you would put the pilot you intend to use on your input-shaft and measure what is going to "individualize" your install. That would seem very easy to confirm using your after install measurement from the mating face of the clutch housing to that of "your" bearing in the crankshaft.

Concur
Measure from the Transmission face (mating to Bell Housing) to tip of transmission input shaft. The pilot bearing (engine end) should be inserted just a bit less than that distance from the face of the Bell Housing.

Dimensions of Black Label Transmission which except for Throwout Bearing Inside Diameter are identical to Blue Label Transmission.
I have installed a Blue Label Transmission in a 1991 ZR-1 and a Black Label Transmission in a 1995 ZR-1.



1 inch or 25.4 mm.................................................. ......................1.373 inch or 34.87 mm


7.50 inches or 190 mm


Pilot Bearing
Throwout Bearings and Clutch Forks

[WVZR-1]

From the mating surface to the clutch housing an LT5 ZF is said to be 190.5mm to the extreme end of the input. 2.5mm end-play maybe considered normal I'd think. I measured several years ago on a '90 but I've got an NOS that's still in the box that I ain't going to open. I really believe that when I measured it was "spot on" but I wasn't that interested. I knew that if it were a "whole bunch longer than 160mm it wasn't an L98/LT1". LOL

On BOP (Buick, Pontiac Olds) that had a "ball bearing" pilot I believe I recall a friend doing a straight edge across the back of the block and measured before, then if the input showed little/no wear installed again just as it was. I can't say that I "got it" but he was particular. The ball bearing was best I recall less than 1/2" so placement was pretty important. Not all of the BOP cranks were machined for bearings - that from time to time was a challenge. The transmission inputs were all the same as any other GM.

[A26B]

This should give you all the information you need to make a determination of the transmission input shaft engagement in the pilot bushing (not bearing).

Measurements were taken of my clutch mock-up parts. Caveat: I do not know for sure whether the pilot bushing is fully nested in the crankshaft, but I have assumed so for the purposes intended.

[WVZR-1]

Jerry - The wear on the input shaft of your demo is I believe very similar to what the OP has mentioned except he's looking at the "results" on the bushing vs the input shaft. I have a '90 here that shows a light "shine" that would indicate that your placement of the bushing is identical to what this input shaft experienced. All .624 of the input has the "shine" - no wear just a "shine".

[Dynomite]

Originally Posted by A26B

This should give you all the information you need to make a determination of the transmission input shaft engagement in the pilot bushing (not bearing).

I ALWAYS use Jerry's Pilot Bearing which has a height of 11/16 inch (.687 inch).

Jerry's Pilot Bearing

You have about 1 inch to work with on the end of the Transmission Input Shaft and I always try to set up the seating depth of the Pilot Bearing to fully install within that last 1 inch of the Transmission Input Shaft.

What I do to insure that.....as I position the transmission using my Transmission jack......it is easy to slide the Transmission Input Shaft Collar through the throwout bearing and the Transmission Input spline through the Clutch Plate (as I recall I have someone depress the Clutch as I install the Transmission).

The Transmission usually slides easily until the tip of the Transmission Input shaft meets up with the Pilot Bearing at which point I have approximately 11/16 inch left for full contact between the Transmission and Bell Housing which dimension is what I am looking for correct engagement of the Transmission Input Shaft with the Pilot Bearing. I then "wiggle" up and down...side to side as I push on Transmission and it always pops in that last (approximately 11/16 inch).

If you do not have approximately 11/16 inch ....Pilot Bearing installation depth may need adjustment.

I do use some good wheel bearing grease on the Pilot Bearing and on the Throwout Bearing, Transmission Shaft Collar before installation of the Transmission.

[A26B]

In my opinion, I would space both, pilot bushing, or pilot bearing, recessed 7/16" (0.437") from the end of the crank. At that location, the pilot bushing will engage the input shaft completely, providing maximum life of the bushing. Likewise, the bearing will work just as well at the same distance.

People I consider experts in this area, Mike Norcia/RAM Clutches, Bill Boudreau/ZR51 Performance, & Jim Jandik/Power Torque Systems recommend the bushing over the bearing, for one primary reason, the bushing will not damage the input shaft, a failed bearing will, due to the hardness of the roller bearings. I follow their recommendations.